Spectral imaging of normal, hydrated, and desiccated porcine skin using polarized light.

Significance: Spectroscopic and structural imaging of tissue layers is important for investigating tissue health. However, investigating superficial tissue is difficult using optical imaging, due to the convolved absorption and backscatter of light from deeper layers. Aim: This report investigates the effects of hydration and desiccation of ex vivo porcine skin on the reflectance of polarized light at different wavelengths (light-emitting diodes). Approach: We developed a spectroscopic polarized imaging system to investigate submicron changes in tissue structures. By separating polarized from depolarized backscattered light, submicron structural changes in subsurface and deeper tissue layers can be separated and monitored. Results: The results demonstrate that (1) polarized light reflectance is about 2%, consistent with ∼6 scattering events, on average; (2) there was little wavelength dependence to the reflectance of polarized light; (3) increased hydration leads to a modest increase in total reflectance (from 0.8 to 0.9), whereas desiccation had little effect; however, hydration did not affect polarized reflectance, but desiccation slightly lowered polarized reflectance. Conclusions: Higher scattering from the reticular dermis was likely due to swelling of collagen fiber bundles in the dermal layers, which increased fibril spacing. The epidermal skin surface showed little change due to the stratum corneum resisting desiccation and maintaining hydration.